Daniele Spallarossa

University of Genoa | UNIGE · Dipartimento di Scienze della terra, dell'ambiente e della vita (DISTAV)

We present STATION (Seismic sTATion and sIte amplificatiON—see Data and Resources), the prototype of an innovative service aimed at providing updated information on specific seismological characteristics of more than 2500 Italian and European seismic stations, belonging to both permanent and temporary networks. The stations are characterized by exp...

This work aims to develop and share a high-quality seismic dataset for the East Anatolian Fault Zone (EAFZ), which is a highly active seismic area that is prone to earthquakes, as evidenced by the two major earthquakes of magnitude 7.8 and 7.6 that occurred on February 6, 2023 in central Türkiye and northern and western Syria. The dataset described...

Obtaining a size estimate of an earthquake that well represents its potential impact is of primary importance in seismology and earthquake engineering. The magnitude scales currently used in earthquake catalogs, mainly Ms and Mw, are not designed to represent the variability of shaking due to variations in high-frequency radiation. Conversely, ML,...

We study the scaling between seismic moment and corner frequency, and the spatial variability of the stress drop, in central and southern Italy. We analyze a data set generated by 28,943 earthquakes that occurred between 2005 and 2023 recorded by 1045 temporary or permanent stations. Considering the trade-off between source and propagation effects,...

We investigate temporal and spatial variations of the spectral decay parameter kappa (κ) before and after the April 6, 2009, L'Aquila earthquake (Mw 6.1), in central Italy. We analyzed foreshocks ten days before and aftershocks occurring ten days and six months after this main event. We select earthquakes with magnitudes Mw ≥ 3.2 registered by the...

Extracting source parameters from recorded spectra requires correction for attenuation effects. In consideration of the trade-off between source and propagation effects, various strategies have been proposed to constrain the inverse problem with a priori assumptions. The objective of this study is to assess the impact of constraining the source spe...

Although physical models are improving our understanding of the crustal processes that lead to large earthquakes, observing their preparatory phases is still challenging. We show that the spatio-temporal evolution of the ground motion of small magnitude earthquakes can shed light on the preparatory phase of three main earthquakes that occurred in c...

The micro-electromechanical system (MEMS)-based seismic network of Trentino (NE Italy) consists of 73 low-cost accelerometers installed close to inhabited areas. These sensors have a suitable sensitivity to detect moderate-to-strong earthquakes but are able to record even weaker seismicity. The densely distributed peak ground acceleration values re...

On-site Earthquake Early Warning (EEW) systems represent an important way to reduce seismic hazard. Since these systems are fast in providing an alert and reliable in the prediction of the ground motion intensity at targets, they are particularly suitable in the areas where the seismogenic zones are close to cities and infrastructures, such as Cent...

To verify the existence of a preparatory process for the 6 February 2023, Mw 7.8 Kahramanmaraş earthquake, southern Türkiye, we analyze the temporal evolution of seismic catalog information for ~ 7500 earthquakes with magnitudes ML ≥ 1.5, which occurred along the main segments of the East Anatolian Fault (EAF) since 2014. We find the EAF fault segm...

How, when and where large earthquakes are generated remain fundamental unsolved scientific questions. Intercepting when a fault system starts deviating from its steady behavior by monitoring the spatio-temporal evolution and dynamic source properties of micro-to-small earthquakes can have high potential as tool for identifying the preparatory phase...

The MEMS-based seismic network of Trentino (NE Italy) consists of 76 low-cost accelerometers installed close to inhabited areas. These sensors have a suitable sensitivity to detect moderate-to-strong earthquakes but are able to record even weaker seismicity. The densely distributed peak ground acceleration values recorded by MEMS and other types of...

As part of the community stress‐drop validation study initiative, we apply a spectral decomposition approach to isolate the source spectra of 556 events occurred during the 2019 Ridgecrest sequence (Southern California). We perform multiple decompositions by introducing alternative choices for some processing and model assumptions, namely: three di...

As part of the community stress-drop validation study, we evaluate the uncertainties of seismic moment M0 and corner frequency fc for earthquakes of the 2019 Ridgecrest sequence. Source spectra were obtained in the companion article by applying the spectral decomposition approach with alternative processing and model assumptions. The objective of t...

How, when and where large earthquakes are generated remain fundamental unsolved scientific questions.Here, we demonstrate that intercepting when a fault system starts deviating from its steady behavior by monitoring the spatio-temporal evolution and dynamic source properties of micro-to-small earthquakescan have high potential as tool for identifyi...

We propose a new fully nonergodic ground motion model for Central Italy, which is one of the most sampled areas in the world after the occurrence of the last seismic sequences of 2009 and 2016–2017. The model predicts 69 ordinates of the Fourier Amplitude Spectrum in the magnitude range 3.2–6.5 and is constrained on a dense set of seismological and...

The protracted nature of the 2016-2017 central Italy seismic sequence, with multiple damaging earthquakes spaced over months, presented serious challenges for the duty seismologists and emergency managers as they assimilated the growing sequence to advise the local population. Uncertainty concerning where and when it was safe to occupy vulnerable s...

In this study we investigate the correlation between the residuals of a neGMM (non-ergodic Ground Motion Model) and the physics-based parameters obtained using a non-parametric GIT approach (Generalized Inversion Technique) to lay the groundwork for the implementation of an ad-hoc FAS (Fourier Amplitude Spectra) neGMM for the Central Italy region....

We consider approximately 23,000 microearthquakes that occurred between 2005 and 2016 in central Italy to investigate the crustal strength before and after the three largest earthquakes of the 2016 seismic sequence (i.e., the Mw 6.2, 24 August 2016 Amatrice, the Mw 6.1, 26 October 2016 Visso, and the Mw 6.5, 30 October 2016 Norcia earthquakes). We...

We investigated the temporal variation of the spectral decay parameter κ before and after two main earthquakes that occurred in the central Italy region, namely the Amatrice (Mw 6.0) of 24 August 2016 and the Norcia (Mw 6.5) of 30 October 2016 earthquakes. For this analysis, we used seismograms from the central Italy dense seismic array stations, a...

Robustness of source parameter estimates is a fundamental issue in understanding the relationships between small and large events, however it is difficult to assess how much of the variability of the source parameters can be attributed to the physical source characteristics or to the uncertainties of the methods and data used to estimate the values...

Plain Language Summary Understanding how the machine generating large earthquakes works is one of the fundamental challenging scientific questions. Pioneering studies have shown that large magnitude earthquakes are sometimes anticipated by foreshocks and slip instabilities. Until now, retrospective analyses of foreshocks during the preparatory phas...

In this article, we apply the reference-rock identification method (RRIM; Lanzano et al., 2020) to the ITalian ACcelerometric Archive, which includes more than 1600 recording stations in Italy and in the neighboring countries, with different levels of site characterization. The RRIM is based on the identification and the evaluation of site paramete...

Fault zones are major sources of hazard for many populated regions around the world. Earthquakes still occur unanticipated, and research has started to observe fault properties with increasing spatial and temporal resolution, having the goal of detecting signs of stress accumulation and strength weakening that may anticipate the rupture. The common...

We used 1029 earthquakes, with magnitudes ranging from M 3.0 to M 6.5, located in central Apennines, Italy, and recorded by 414 local stations to study the variation of the quality factor QS of shear waves with depth. We first determined average nonparametric attenuation functions in the frequency band from 0.5 to 20 Hz and hypocenter distances les...

In recent years, new approaches for developing earthquake rupture forecasts (ERFs) have been proposed to be used as an input for probabilistic seismic hazard assessment (PSHA). Zone-based approaches with seismicity rates derived from earthquake catalogs are commonly used in many countries as the standard for national seismic hazard models. In Italy...

We present Rapid Assessment of MOmeNt and Energy Service (RAMONES), a service for disseminating through a web interface, the estimates of seismic moment (M0) and radiated energy (ER) for earthquakes occurring in central Italy with local magnitudes above 1.7. The service is based on a fully-automatic procedure developed for downloading and processin...

This work focuses on site response analyses in the Amatrice area (Central Italy), taking advantage of the 3A temporary seismic network, installed after the first shock (MW 6.0) of the 2016–2017 seismic sequence, and of a detailed site characterization. Classical empirical methods are applied on seismic signals to evaluate their capabilities to infe...

The 2016–17 central Italy earthquake sequence began with the first mainshock near the town of Amatrice on August 24 (MW 6.0), and was followed by two subsequent large events near Visso on October 26 (MW 5.9) and Norcia on October 30 (MW 6.5), plus a cluster of 4 events with MW > 5.0 within few hours on January 18, 2017. The affected area had been m...

This paper describes the seismological analyses performed within the framework of the seismic microzonation study for the reconstruction of 138 municipalities damaged by the 2016–2017 sequence in Central Italy. Many waveforms were recorded over approximately 15 years at approximately 180 instrumented sites equipped with permanent or temporary stati...

We apply a spectral decomposition approach to isolate the source spectra from propagation and site effects and, in turn, to estimate the source parameters of small-to-moderate earthquakes that occurred in central Italy. The data set is composed of about 400,000 waveforms relevant to 4111 earthquakes in the moment magnitude range 1.5–6.5, recorded b...

To evaluate the site response using both empirical approaches (e.g. standard spectral ratio, ground motion models (GMMs), generalized inversion techniques, etc.) and numerical 1- D/2-D analyses, the definition of the reference motion, that is the ground motion recorded at stations unaffected by site-effects due to topographic, stratigraphic or basi...

On-Site Earthquake Early Warning Systems (EEW) exploit predictive models relating features extracted over the P-wave window to S-wave ground motion parameters. These models are usually calibrated considering recordings from multiple stations and combining datasets from different regions under the ergodic assumption. Here, we show that the local sit...

Damaging earthquakes result from the evolution of stress in the brittle upper-crust, but the understanding of the mechanics of faulting cannot be achieved by only studying the large ones, which are rare. Considering a fault as a complex system, microearthquakes allow to set a benchmark in the system evolution. Here, we investigate the possibility t...

The first mainshock (Mw 6.0) of the 2016 Central Italy seismic sequence, severely struck the Amatrice village and the surrounding localities. After few days, some Italian Institutions, coordinated by the "Center for Seismic Microzonation and its applications", carried out several preparatory activities for seismic microzonation of the area. A tempo...

We derive a set of regional ground-motion prediction equations (GMPEs) in the Fourier amplitude spectra (FAS-GMPE) and in the spectral acceleration (SAGMPE) domains for the purpose of interpreting the between-event residuals in terms of source parameter variability. We analyze a dataset of about 65,000 recordings generated by 1400 earthquakes (mome...

The present work aims to suggest an innovative solution for seismic monitoring stations’ endurance. These stations are characterized by many different problems, such as lightning vulnerability, energy independence and noises disturbance. The suggested technology, for this type of application, is an improved bladeless turbo-expander patented by Niko...

The size of an earthquake can be defined either from the seismic moment (M 0) or in terms of radiated seismic energy (E r). These two parameters look at the source complexity from different perspectives: M 0 is a static measure of the earthquake size, whereas E r is related to the rupture kinematics and dynamics. For practical applications and for...

We introduce in the on-site earthquake early warning (EEW) a partially non-ergodic perspective from the site effects point of view. We consider the on-site EEW approach where the peak ground velocity (PGV) for S-waves is predicted from an early estimate, over the P-waves, of either the peak-displacement (PD) or cumulative squared velocity (IV2). Th...

The AlpArray programme is a multinational, European consortium to advance our understanding of orogenesis and its relationship to mantle dynamics, plate reorganizations, surface processes and seismic hazard in the Alps–Apennines–Carpathians–Dinarides orogenic system. The AlpArray Seismic Network has been deployed with contributions from 36 institut...

The 2016-2017 Central Italy seismic sequence ruptured overlapping normal faults of the Apennines mountain chain, in nine earthquakes with magnitude Mw > 5 within a few months. Here we investigate the structure of the fault system using an extensive aftershock data set, from joint permanent and temporary seismic networks, and 3-D Vp and Vp/Vs veloci...

Ground-motion prediction equations (GMPEs) are calibrated to predict the intensity of ground shaking at any given location, based on earthquake magnitude, source-to-site distance, local soil amplifications, and other parameters. GMPEs are generally assumed to be independent of time; however, evidence is increasing that large earthquakes modify the...

In this work the scaling of seismic moment (M0) and radiated energy (Er) is investigated for almost 800 earthquakes of the 2016-17 Amatrice-Norcia sequences in Italy, ranging in moment magnitude (Mw) from 2.5 to 6.5. The analysis of the M0-to-Er scaling highlights a breaking of the source self-similarity, with higher stress drops for larger events....

The RSNI-Picker2 (Regional Seismic network of Northwestern Italy, University of Genova) automatic phase detector, picker, and locator is presented, as well as the analysis of its performance in real-time monitoring of earthquakes and nontectonic events. The major improvements of this algorithm with respect to previous ones are the iterative couplin...

In this study, we analyzed 10 yrs of seismicity in central Italy from 2008 to 2017, a period witnessing more than 1400 earthquakes in the magnitude range 2.5 ≤ Mw ≤ 6.5. The data set includes the main sequences that have occurred in the area, including those associated with the 2009 Mw 6.3 L’Aquila earthquake and the 2016–2017 sequence (Mw 6.2 Amat...

Since the beginning of the 1980s, when Mandelbrot observed that earthquakes occur on 'fractal' self-similar sets, many studies have investigated the dynamical mechanisms that lead to self-similarities in the earthquake process. Interpreting seismicity as a self-similar process is undoubtedly convenient to bypass the physical complexities related to...

The zonation presented in this study has been developed with the aim of applying it as a branch of the logic tree that will be used for the new Italian seismic hazard map, presently in preparation according to the approach of seismotectonic probabilism. With respect to the zonation used for the present official seismic hazard map of Italy, the zona...

In this study, we analyse a regional data set composed by about 9000 waveforms from 231 earthquakes in the magnitude range from 3 to 6 and recorded in central Italy in the time period 2008-2013. We derive a seismological model whose source, attenuation and site parameters are used to explain the ground motion variability associated with a set of gr...

The article presents a comparison of different probabilistic methods for ground motion hazard assessments that include site effects. The approaches examined here were selected and refined during the different phases of the S2-Project, which this journal volume is addressed to. Different procedures characterized by different levels of sophistication...

In this study, we apply an empirical scoring method to evaluate the feasibility of probabilistic seismic hazard analyses (PSHAs) at regional scale in Italy accounting for site amplification, which is taken into account through the application of a set of ground motion prediction equations (GMPEs) defined for specific ground types. Precisely, this m...

This study compares 12 hazard models based on dated and recent ground-motion prediction equations (GMPEs) to evaluate the improvement provided by new equations on probabilistic seismic-hazard assessments in Italy. To this end, a statistical procedure is applied to score the outcomes of each hazard model at 56 different accelerometric sites that hav...

The growing number of permanent and temporary seismic stations has recently led to a huge amount of available seismic recordings. To take advantage of all the information contained in these data, reliable automatic procedures are increasingly required. In particular, an automatic phase picking engine able to work in a very short time like a seismol...

The Trentino region (NE Italy) shows moderate-to-low instrumental seismicity, mainly concentrated in its southern (Lake Garda and Lessini) and eastern portions (Venetian southern alpine front), as also confirmed by historical earthquakes. This area is characterized by a complex crustal structure, where dominant fault systems (namely Valsugana, Giud...

In this work, we test a fully automatic procedure to obtain local earthquake tomography (LET), starting from seismic waveforms and applying the capability of the automatic phase picker and locator engine “RSNI-Picker” (Spallarossa et al., 2014), which is based on a multistep iterative procedure working on P and S arrival times. This code is current...

In this study we derive a spectral model describing the source, propagation and site characteristics of S waves recorded in central Italy. To this end, we compile and analyse a high-quality data set composed of more than 9000 acceleration and velocity waveforms in the local magnitude (M-1) range 3.0-5.8 recorded at epicentral distances smaller than...

The purpose of this work is to study seismic amplification effects at four sites hosting recording stations of the National Accelerometric Network (RAN) managed by the national Department of Civil Protection. At all sites, which are located in the Piedmont region (Northwestern Italy), both active and passive seismic prospecting methods are used, al...

A revised seismic catalogue (1994–2007) for the central–eastern Alps (N Italy) is presented. 396 earthquake relocations, for local magnitudes in the 1.2–5.3 range, are performed using a 3D crustal velocity stucture and probabilistic locations. The location procedure is validated by computing a set of 41 quarry shot solutions and all the results, bo...

The impact on probabilistic ground-motion hazard of different definitions of the horizontal component of ground shaking is examined. The scope is to highlight how such a minor detail within the complex computation chain of a probabilistic seismic- hazard assessment can play a crucial role on final results. This is achieved by comparing hazard maps...

The aim of this work is to describe the seismicity of Northwestern Italy from the very detailed picture provided by 30 years of accurate instrumental recordings coming from the Regional Seismic Network of Northwestern Italy (RSNI—University of Genoa). In an attempt to provide, for the first time, a comprehensive view of the seismicity in the area,...